Method for registering a deposited material with channel plate channels, and switch produced using same

ABSTRACT

A method for depositing material on a channel plate such that the material is registered to one or more channels formed in the channel plate includes filling at least one of the channels with a resist that is not wetted by the material; depositing the material on at least a region of the channel plate that includes at least part of the resist; and then removing the resist. The method may be used, in one embodiment, to apply an adhesive or gasket material that is used in assembling a switch.

BACKGROUND

Fluid-based switches such as liquid metal micro switches (LIMMS) aredisclosed in the following patent and patent applications (the teachingsof which are hereby incorporated by reference): U.S. Pat. No. 6,323,447of Kondoh et al. entitled “Electrical Contact Breaker Switch, IntegratedElectrical Contact Breaker Switch, and Electrical Contact SwitchingMethod”; U.S. patent application of Marvin Glenn Wong entitled “APiezoelectrically Actuated Liquid Metal Switch” (Ser. No. 10/137,691,filed May 2, 2002); and U.S. patent application of Marvin Glenn Wongentitled “Laser Cut Channel Plate for a Switch” (Ser. No. 10/317,932,filed Dec. 12, 2002).

One way to manufacture the switches disclosed in the above-referencedpatent and patent applications is to 1) deposit an adhesive on a channelplate, and then 2) seal the desired combination of switching fluid(s),actuating fluid(s) and/or other switch components between the channelplate and a substrate.

When depositing the adhesive on the channel plate, it is typicallydesirable to “register” the adhesive with the channels of the channelplate. That is, it is desirable to deposit the adhesive on the channelplate so that it extends precisely up to, but not into, the channels ofthe channel plate. In this manner, the adhesive does not contribute toincreasing or decreasing the volumes of cavities that are defined by thechannels when the channel plate is sealed to the substrate.

SUMMARY OF THE INVENTION

One aspect of the invention is embodied in a method for depositingmaterial on a channel plate such that the material is registered to oneor more channels formed in the channel plate. The method comprises 1)filling at least one of the channels with a resist that is not wetted bythe material, 2) depositing the material on at least a region of thechannel plate that at least abuts a portion of the resist, and then 3)removing the resist.

Another aspect of the invention is embodied in a switch produced by 1)forming at least one channel in a channel plate, 2) filling at least oneof the channels with a resist that is not wetted by a material that isto be applied to the channel plate, 3) depositing the material on atleast a region of the channel plate that at least abuts a portion of theresist, 4) removing the resist, and 5) aligning the at least one channelformed in the channel plate with at least one feature on a substrate,and sealing, by means of the deposited material, at least a switchingfluid between the channel plate and the substrate.

Other embodiments of the invention are also disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments of the invention are illustrated in thedrawings, in which:

FIG. 1 illustrates an exemplary plan view of a channel plate for aswitch;

FIG. 2 illustrates a first cross-section of the FIG. 1 channel plate;

FIG. 3 illustrates a second cross-section of the FIG. 1 channel plate;

FIG. 4 illustrates a method for depositing material on a channel platesuch that the material is registered to one or more channels formed inthe FIG. 1 channel plate;

FIGS. 5 & 6 illustrate how channels of the FIG. 1 channel plate may befilled with a resist;

FIG. 7 illustrates the channel plate of FIG. 5 or 6, after abrasion;

FIG. 8 illustrates the deposition of a material on the FIG. 1 channelplate while the channels of the channel plate are filled with a resist;

FIG. 9 illustrates the rounding of deposited material corners at theedges of a channel plate channel filled with resist;

FIG. 10 illustrates the leaning of deposited material edges at the edgesof a channel plate channel filled with resist;

FIG. 11 illustrates the channel plate cross-section shown in FIG. 8,after the resist has been removed from the channel plate's channels;

FIG. 12 illustrates how the FIG. 1 channel plate may be sealed to asubstrate;

FIG. 13 illustrates a first exemplary embodiment of a switch;

FIG. 14 illustrates an exemplary method for producing the switchillustrated in FIG. 13;

FIGS. 15 & 16 illustrate the metallization of portions of the FIG. 1channel plate; and

FIG. 17 illustrates a second exemplary embodiment of a switch.

DETAILED DESCRIPTION OF THE INVENTION

When depositing material on a channel plate, it is sometimes desirableto register the material with one or more channels that are formed inthe channel plate. That is, it is sometimes desirable to depositmaterial on a channel plate such that it extends precisely up to, butnot into, the channels of the channel plate.

Fluid-based switches represent one application in which channelregistration of a material is desirable. For example, during themanufacture of a switch in accordance with the patent and patentapplications disclosed in the Background section of this disclosure, anadhesive may be applied to a channel plate for the purpose of sealingthe channel plate to a substrate. Between the channel plate andsubstrate are sealed a combination of switching fluid(s), actuatingfluid(s) and/or other switch components. When depositing the adhesive onthe channel plate, it is typically desirable to register the adhesivewith the channels of the channel plate so that the adhesive does notincrease or decrease the volumes of cavities that are defined by thechannels when the channel plate is sealed to the substrate.

One way to register an adhesive with the channels of a channel plate isto deposit a layer of adhesive on the channel plate, partially cure it,deposit a layer of photoresist on top of the adhesive, photodefine thephotoresist layer, and then sandblast the adhesive from the channelplate's channels. However, disadvantages of this process include 1)relatively large tolerances in adhesive channel registration, as well as2) rough channel surfaces as a result of the sandblasting. The processalso places limits on the types of substrates that may be used for thechannel plate, as well as the geometries of channel structures that canbe accommodated.

The inventors have therefore devised new methods for depositing materialon a channel plate, as well as new switches that are produced inaccordance with the methods. The new methods provide better registrationof deposited materials to the channel or channels that have been formedin the channel plate.

FIGS. 1-3 illustrate a first exemplary embodiment of a channel plate100. FIG. 1 illustrates a plan view of the channel plate 100, whileFIGS. 2 & 3 illustrate two exemplary cross-sections of the channel plate100. Such a channel plate might be used, for example, in a fluid-basedswitch such as a LIMMS. By way of example, the channel plate 100 isshown to comprise five different channels 102, 104, 106, 108, 110 ofvarying depths. However, it is envisioned that more or fewer channelsmay be formed in a channel plate, depending on the configuration of theswitch in which the channel plate is to be used. The base material forthe channel plate 100 may be glass, ceramic, metal or polymer, to name afew. Depending on the base material used and the channel tolerancesdesired, channels may be machined, injection molded, press molded, slumpmolded, etched, laser cut, ultrasonically milled, laminated, stamped orotherwise formed in a channel plate 100.

For the purpose of this description, “channel” is defined to be any sortof groove, trough, pit or other feature that creates a recess in achannel plate that extends below the uppermost surface of the channelplate.

In accordance with the invention, FIG. 4 illustrates a method 400 fordepositing material on a channel plate 100 so that the depositedmaterial is registered to one or more channels 102-110 formed in thechannel plate 100. The method 400 comprises filling 402 at least one ofthe channel plate's channels 102-110 with a resist that is not wetted bythe material that is to be deposited on the channel plate 100. Althoughit is envisioned that all of a channel plate's channels 102-110 willtypically be filled with the resist, there may be applications in whichit might be desirable to fill or coat some of a channel plate's channelswith a deposited material. In these applications, the channels that areto be filled or coated with the deposited material are not filled withthe resist.

Channels 104, 106 may be filled with resist 500 as shown in FIG. 5 or 6,for example. In FIG. 5, a resist 500 is applied only to a channelplate's channels 104, 106. Alternatively, and as shown in FIG. 6, aresist 500 may be applied to an entire surface of a channel plate 100such that it extends beyond the boundaries of a channel plate's channels104, 106. Although application of a resist 500 as shown in FIG. 6requires that portions of the resist 500 that fall outside of thechannel plate's channels 104, 106 be removed prior to the next step ofthe FIG. 4 method, application of a resist 500 as shown in FIG. 6 may beeasier and quicker than application of a resist 500 as shown in FIG. 5.

Regardless of how a resist 500 is applied to a channel plate 100, it maybe desirable to abrade the channel plate to make the resist 500 planarwith the surface of the channel plate 100, or to better definetransitions between the resist 500 and the edges of channels 104, 106that are filled with the resist 500. Following abrasion, the channelplates 100 with resist 500 shown in FIGS. 5 and 6 may appear asillustrated in FIG. 7.

By way of example, a channel plate 100 may be abraded by means ofchemical mechanical planarization, or grinding and polishing.

Although a channel plate 100 may be abraded solely for the purpose ofremoving excess resist 500, a channel plate 100 may also be abraded forthe purpose of flattening the surface or surfaces of the channel platebearing resist-filled channels 104, 106. If the material to be depositedon a channel plate 100 is an adhesive or gasket material, flattening thechannel plate 100 may help the channel plate 100 achieve a better bondto (or fit with) a part to which it is later mated.

After filling one or more channels 104, 106 with a resist 500, a desiredmaterial 800 is deposited 404 (FIG. 4) on at least a region of thechannel plate 100 that at least abuts a portion of the resist 500 (seeFIG. 8). In other words, the material 800 need not be deposited over theentirety of a channel plate's surface, nor need the material 800 bedeposited over a region of the channel plate 100 encompassing theentirety of a resist filled channel 104. Thus, for example, the material800 may be deposited over a region 112 encompassing one end of a channel104 that is filled with resist 500 (see FIG. 1), or the material 800 maybe deposited primarily on one side 114, 116 of a channel 104 that isfilled with resist 500. Alternately, the material 800 may be depositedover the entirety of one or more of a channel plate's surfaces.

By way of example, a material layer 800 may be deposited on a channelplate 100 by means of spin coating or spray coating. Since the resist500 is selected so as not to be wetted by the material 800 that isdeposited on the channel plate 100, and as a result of the depositedmaterial's surface tension, the deposited material 800 will only extendup to the borders of the resist 500. Thus, if the resist 500 isprecisely registered to the boundaries of a channel plate's channels104, 106, so too will the deposited material 800 be registered to theboundaries of the channels 104, 106.

FIG. 9 illustrates how the corners 900, 902 of a deposited material 800can “round” at the boundaries of a channel plate channel 104. Thiseffect may be accentuated as the thickness of the deposited material 800increases. If desired, the deposited material 800 may be abraded toremove that portion of the material where rounding is present.

FIG. 10 illustrates a possibly undesirable effect of depositing toothick of a material layer 800 on a channel plate 100. As shown in FIG.10, a layer 800 that is too thick may “lean” over a channel platechannel 104. Again, the deposited material 800 may be abraded to removethat portion of the material that leans excessively. Alternately, athinner layer of material 800 may be deposited on the channel plate 100.

After the material 800 has been deposited, the resist 500 may be removed406 (see FIG. 11). By way of example, the resist 500 may be removedusing an etching or developing process. Depending on the nature of thedeposited material 800, and the process used to remove the resist 500,it may be necessary to cure the deposited material 800 prior to removingthe resist 500. The curing may be achieved by exposing the depositedmaterial 800 to ambient conditions for a period of time, by heating thedeposited material 800, by submersing the deposited material 800 in anappropriate solution, or by other means. If necessary, the depositedmaterial 800 may also be cured (or cured further) after the resist 500is removed.

If desired, the channel plate 100, with deposited material 800 thereon,may be mated to another part (e.g., in the case of a fluid-based switchwherein the deposited material 800 is an adhesive or gasket, the part towhich the channel plate 100 is mated may be a switch substrate 1200(FIG. 12)).

Given that fluid-based switch manufacture is one potential and intendedapplication for the FIG. 4 method, some exemplary fluid-based switchesto which the FIG. 4 method can be applied will now be described.

FIG. 13 illustrates a first exemplary embodiment of a switch 1300. Theswitch 1300 comprises a channel plate 1302 defining at least a portionof a number of cavities 1306, 1308, 1310. The remaining portions of thecavities 1306-1310, if any, may be defined by a substrate 1304 to whichthe channel plate 1302 is sealed. Exposed within one or more of thecavities are a plurality of electrodes 1312, 1314, 1316. A switchingfluid 1318 (e.g., a conductive liquid metal such as mercury) held withinone or more of the cavities serves to open and close at least a pair ofthe plurality of electrodes 1312-1316 in response to forces that areapplied to the switching fluid 1318. An actuating fluid 1320 (e.g., aninert gas or liquid) held within one or more of the cavities serves toapply the forces to the switching fluid 1318.

In one embodiment of the switch 1300, the forces applied to theswitching fluid 1318 result from pressure changes in the actuating fluid1320. The pressure changes in the actuating fluid 1320 impart pressurechanges to the switching fluid 1318, and thereby cause the switchingfluid 1318 to change form, move, part, etc. In FIG. 13, the pressure ofthe actuating fluid 1320 held in cavity 1306 applies a force to part theswitching fluid 1318 as illustrated. In this state, the rightmost pairof electrodes 1314, 1316 of the switch 1300 are coupled to one another.If the pressure of the actuating fluid 1320 held in cavity 1306 isrelieved, and the pressure of the actuating fluid 1320 held in cavity1310 is increased, the switching fluid 1318 can be forced to part andmerge so that electrodes 1314 and 1316 are decoupled and electrodes 1312and 1314 are coupled.

By way of example, pressure changes in the actuating fluid 1320 may beachieved by means of heating the actuating fluid 1320, or by means ofpiezoelectric pumping. The former is described in U.S. Pat. No.6,323,447 of Kondoh et al. entitled “Electrical Contact Breaker Switch,Integrated Electrical Contact Breaker Switch, and Electrical ContactSwitching Method”. The latter is described in U.S. patent applicationSer. No. 10/137,691 of Marvin Glenn Wong filed May 2, 2002 and entitled“A Piezoelectrically Actuated Liquid Metal Switch”. Although the abovereferenced patent and patent application disclose the movement of aswitching fluid by means of dual push/pull actuating fluid cavities, asingle push/pull actuating fluid cavity might suffice if significantenough push/pull pressure changes could be imparted to a switching fluidfrom such a cavity. In such an arrangement, the channel plate for theswitch could be constructed similarly to the channel plate 100 disclosedherein.

The channel plate 1302 of the switch 1300 may have a plurality ofchannels 102-110 formed therein, as illustrated in FIGS. 1-3. In oneembodiment of the switch 1300, the first channel 104 in the channelplate 100 (or 1302) defines at least a portion of the one or morecavities 1308 that hold the switching fluid 1318. By way of example,this switching fluid channel 104 may have a width of about 200 microns,a length of about 2600 microns, and a depth of about 200 microns.

A second channel (or channels 102, 106) may be formed in the channelplate 100 (or 1302) so as to define at least a portion of the one ormore cavities 1306, 1310 that hold the actuating fluid 1320. By way ofexample, these actuating fluid channels 102, 106 may each have a widthof about 350 microns, a length of about 1400 microns, and a depth ofabout 300 microns.

A third channel (or channels 108, 110) may be formed in the channelplate 100 (or 1302) so as to define at least a portion of one or morecavities that connect the cavities 1306-1310 holding the switching andactuating fluids 1318, 1320. By way of example, the channels 108, 110that connect the actuating fluid channels 102, 106 to the switchingfluid channel 104 may each have a width of about 100 microns, a lengthof about 600 microns, and a depth of about 130 microns.

An exemplary method 1400 for producing the switch 1300 illustrated inFIG. 13 is illustrated in FIG. 14. The method 1400 commences with theformation 1402 of at least one channel 102-110 in a channel plate 100(or 1302). At least one of the channels 104 is then filled 1404 with aresist 500 that is not wetted by a material 800 that is to be depositedon the channel plate 100. Thereafter, the material 800 is deposited 1406on at least a region of the channel plate 100 that at least abuts aportion of the resist 500. The material 800 may be applied in a varietyof ways that include, for example, spin coating and spray coating.

After depositing the material 800, the resist 500 is removed 1408.Optionally, the deposited material 800 may be cured prior to removingthe resist 500. Finally, the at least one channel 102-110 formed in thechannel plate 100 (or 1302) is aligned with at least one feature on asubstrate 1304, and at least a switching fluid 1318 is sealed 1410between the channel plate 1302 and the substrate 1304, by means of thedeposited material 800. As taught in FIG. 13, an actuating fluid 1320may also be sealed between the channel plate 1302 and substrate 1304.

The material 800 deposited on the channel plate 1302 may be, forexample, an adhesive or gasket material. One suitable adhesive is Cytop™(manufactured by Asahi Glass Co., Ltd. of Tokyo, Japan). Cytop™ comeswith two different adhesion promoter packages, depending on theapplication. When a channel plate 100 has an inorganic composition,Cytop™'s inorganic adhesion promoters should be used and an organicresist 500 should be used. Similarly, when a channel plate 100 has anorganic composition, Cytop™'s organic adhesion promoters should be used,and an inorganic resist 500 should be used (including, possibly, aninorganic resist such as a thin sputtered-on coating of metal or glass).

Optionally, and as illustrated in FIGS. 15 & 16, portions of a channelplate 100 (or 1302) may be metallized (e.g., via sputtering orevaporating through a shadow mask, or via etching through a photoresist)for the purpose of creating “seal belts” 1502, 1504, 1506. Seal belts1502-1506 may be created before or after the deposition of adhesive orgasket material on a channel plate 100. The creation of seal belts1502-1506 within a switching fluid channel 104 provides additionalsurface areas to which a switching fluid may wet. This not only helps inlatching the various states that a switching fluid can assume, but alsohelps to create a sealed chamber from which the switching fluid cannotescape, and within which the switching fluid may be more easily pumped(i.e., during switch state changes).

Additional details concerning the construction and operation of a switchsuch as that which is illustrated in FIG. 13 may be found in theafore-mentioned patent of Kondoh et al. and patent application of MarvinWong.

FIG. 17 illustrates a second exemplary embodiment of a switch 1700. Theswitch 1700 comprises a channel plate 1702 defining at least a portionof a number of cavities 1706, 1708, 1710. The remaining portions of thecavities 1706-1710, if any, may be defined by a substrate 1704 to whichthe channel plate 1702 is sealed. Exposed within one or more of thecavities are a plurality of wettable pads 1712-1716. A switching fluid1718 (e.g., a liquid metal such as mercury) is wettable to the pads1712-1716 and is held within one or more of the cavities. The switchingfluid 1718 serves to open and block light paths 1722/1724, 1726/1728through one or more of the cavities, in response to forces that areapplied to the switching fluid 1718. By way of example, the light pathsmay be defined by waveguides 1722-1728 that are aligned with translucentwindows in the cavity 1708 holding the switching fluid. Blocking of thelight paths 1722/1724, 1726/1728 may be achieved by virtue of theswitching fluid 1718 being opaque. An actuating fluid 1720 (e.g., aninert gas or liquid) held within one or more of the cavities serves toapply the forces to the switching fluid 1718.

Forces may be applied to the switching and actuating fluids 1718, 1720in the same manner that they are applied to the switching and actuatingfluids 1718, 1720 in FIG. 13.

The channel plate 1702 of the switch 1700 may have a plurality ofchannels 102-110 formed therein, as illustrated in FIGS. 1-3. In oneembodiment of the switch 1700, the first channel 104 in the channelplate 100 (or 1702) defines at least a portion of the one or morecavities 1708 that hold the switching fluid 1718.

A second channel (or channels 102, 106) may be formed in the channelplate 100 (or 1702) so as to define at least a portion of the one ormore cavities 1706, 1710 that hold the actuating fluid 1720.

A third channel (or channels 108, 110) may be formed in the channelplate 100 (or 1702) so as to define at least a portion of one or morecavities that connect the cavities 1706-1710 holding the switching andactuating fluids 1718, 1720.

Additional details concerning the construction and operation of a switchsuch as that which is illustrated in FIG. 17 may be found in theafore-mentioned patent of Kondoh et al. and patent application of MarvinWong. Furthermore, an adhesive or gasket layer, as well as seal belts,may be applied to the switch's channel plate 1702 as described supra,and as shown in FIGS. 14-16.

The use of channel plates is not limited to the switches 1300, 1700disclosed in FIGS. 13 & 17 and may be undertaken with other forms ofswitches that comprise, for example, 1) a channel plate defining atleast a portion of a number of cavities, a first cavity of which isdefined by an ultrasonically milled channel in the channel plate, and 2)a switching fluid, held within one or more of the cavities, that ismovable between at least first and second switch states in response toforces that are applied to the switching fluid.

While illustrative and presently preferred embodiments of the inventionhave been described in detail herein, it is to be understood that theinventive concepts may be otherwise variously embodied and employed, andthat the appended claims are intended to be construed to include suchvariations, except as limited by the prior art.

What is claimed is:
 1. A switch, produced by: a) forming at least onechannel in a channel plate; b) filling at least one of the channels witha resist that is not wetted by a material that is to be deposited on thechannel plate; c) depositing the material on at least a region of thechannel plate that at least abuts a portion of the resist, the materialregistering with at least one channel edge as a result of the material'sabutment to the resist; d) removing the resist; and e) aligning the atleast one channel formed in the channel plate with at least one featureon a substrate, and sealing, by means of the deposited material, atleast a switching fluid between the channel plate and the substrate. 2.The switch of claim 1, further comprising, curing the deposited materialprior to removing the resist.
 3. The switch of claim 1, wherein thedeposited material is an adhesive.
 4. The switch of claim 1, wherein thedeposited material is a gasket material.
 5. The switch of claim 1,wherein the material is deposited by means of spin coating.
 6. Theswitch of claim 1, wherein the material is deposited by means of spraycoating.
 7. The switch of claim 1, wherein: a) a first channel formed inthe channel plate is a channel for holding the switching fluid; and b)the channel for holding the switching fluid is filled with the resist.8. The switch of claim 7, wherein: a) a second channel formed in thechannel plate is an actuating fluid channel; b) the actuating fluidchannel is filled with the resist; and c) the method further comprisessealing an actuating fluid between the channel plate and the substrate,said actuating fluid serving to apply forces to said switching fluid tothereby change the state of said switching fluid.
 9. The switch of claim1, wherein: a) the at least one channel formed in the channel platecomprises a channel for holding the switching fluid, a pair of channelsfor holding an actuating fluid, said actuating fluid serving to applyforces to said switching fluid to thereby change the state of saidswitching fluid, and a pair of channels connecting corresponding ones ofthe channels holding the actuating fluid to the channel holding theswitching fluid; and b) all of the channels are filled with the resist.10. A channel plate for a switch, comprising: a) at least one channelformed therein; b) a removable resist filling at least one of saidchannels, the resist being unwettable by a material that is to bedeposited on the channel plate; c) said material, deposited on at leasta region of the channel plate that at least abuts a portion of theresist, the material thereby registering with at least one channel edgeas a result of the material's abutment to the resist.
 11. The channelplate of claim 10, wherein the deposited material is an adhesive. 12.The channel plate of claim 10, wherein the deposited material is agasket material.